Single crystal like TiO2 nanotubes with preferential orientation along the [001] direction, parallel to the growth direction of nanotubes, that offer ease of charge transport much higher than reported so far, are fabricated using a cost... more
Single crystal like TiO2 nanotubes with preferential orientation along the [001] direction, parallel to the growth direction of nanotubes, that offer ease of charge transport much higher than reported so far, are fabricated using a cost effective two step technique. The success of this method to grow the nanotubes with the anomalous intense [001] preferential orientation is attributed to the zinc assisted minimization of the (001) surface energy. The single crystal like TiO2 nanotubes show superior performance as supercapacitor electrodes compared to the normal polycrystalline titanium dioxide nanotubes.
Research Interests:
Simple electrochemical method for the hydrogenation of metal oxides in 10 s.Water with small amount of fluorine ions is used as electrolyte.No microstructural variation during the hydrogenation process.Significantly higher absorbance in... more
Simple electrochemical method for the hydrogenation of metal oxides in 10 s.Water with small amount of fluorine ions is used as electrolyte.No microstructural variation during the hydrogenation process.Significantly higher absorbance in the visible and IR region of light.Safe, low cost and fast process and can be adapted for large scale synthesis.Hydrogenation of oxides such as TiO2 is so far considered as a time consuming and complex process which requires high temperature annealing in hydrogen atmosphere. In this work, an electrochemical method for the hydrogenation of metal oxides is introduced. The electrochemical hydrogenation process is a low cost process which requires only a few seconds for synthesizing the black semiconducting oxides. Water with small amount (0.2 vol%) of ionic species like fluorine ions is used as electrolyte. The black semiconducting oxides prepared using the electrochemical hydrogenation process exhibit very good absorption of light in visible region.
Research Interests:
Research Interests:
ABSTRACT Though researchers worldwide have attempted to fabricate faceted titania nanoparticles with a higher fraction of {001} facets, which have high surface energy, the approaches have focused on use of either a very aggressive heating... more
ABSTRACT Though researchers worldwide have attempted to fabricate faceted titania nanoparticles with a higher fraction of {001} facets, which have high surface energy, the approaches have focused on use of either a very aggressive heating schedule or highly corrosive chemicals like HF. The current manuscript reports a simple method for the transformation of the titania nanotubes to faceted nanoparticles (size varying from 15 nm - 120 nm) at relatively low temperatures and heating rates, without the use of any other corrosive chemicals, utilizing only the electrolyte inside the titania nanotubes remnant from the anodization of the titanium substrate. The formation of faceted nanoparticles was found to be strongly dependent on fluorine concentration and on initial state of titania nanotubes (amorphous/crystalline) and annealing temperature. The formation of the unique ‘nanorod in nanoporous’ structures has been reported for the first time. The current manuscript deals with a detailed study of the formation of these unique nanostructures and proposes a mechanism for the same.
Research Interests:
Research Interests:
ABSTRACT Hydrogenation of oxides such as TiO2 is so far considered as a time consuming and complex process which requires high temperature annealing in hydrogen atmosphere. In this work, an electrochemical method for the hydrogenation of... more
ABSTRACT Hydrogenation of oxides such as TiO2 is so far considered as a time consuming and complex process which requires high temperature annealing in hydrogen atmosphere. In this work, an electrochemical method for the hydrogenation of metal oxides is introduced. The electrochemical hydrogenation process is a low cost process which requires only a few seconds for synthesizing the black semiconducting oxides. Water with small amount (0.2 vol%) of ionic species like fluorine ions is used as electrolyte. The black semiconducting oxides prepared using the electrochemical hydrogenation process exhibit very good absorption of light in visible region.
Research Interests:
ABSTRACT Self-aligned titania nanotubes have been fabricated by electrochemical anodic oxidation of titanium foil in organic electrolyte containing fluoride ions. Varying the water content in electrolyte used during anodization results in... more
ABSTRACT Self-aligned titania nanotubes have been fabricated by electrochemical anodic oxidation of titanium foil in organic electrolyte containing fluoride ions. Varying the water content in electrolyte used during anodization results in a fluorine concentration gradient along the titania nanotubes. A consequence of this is the dependence of the extent and morphology of the nanograss layer on the water content in the electrolyte. A mechanism has been proposed for the formation of the nanograss layer over titania nanotubes and its different morphologies viz. ring type or vertical splitting.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Pure and Mg-doped SnO 2 films are prepared through a spray pyrolysis reaction, wherein the light doping keeps up the tetragonal rutile SnO 2 polycrystalline structure. When the compositional ratio of Mg:SnO 2 is 0.6 wt%, the obtained... more
Pure and Mg-doped SnO 2 films are prepared through a spray pyrolysis reaction, wherein the light doping keeps up the tetragonal rutile SnO 2 polycrystalline structure. When the compositional ratio of Mg:SnO 2 is 0.6 wt%, the obtained crystallites have a size of 36 nm and show the highest response of 93% in 1000 ppm LPG, which is nearly three times larger than that of undoped SnO 2. Storage under humid atmospheric conditions influences the gas response of tin oxide thin film sensors. To analyze the cause, the morphology, microstructure and composition of the films are studied in relation to the gas response of the film, with a collection on films having maximum sensitivity. It is observed that a thin surface coverage of hydroxyl groups is developed during storage at room atmosphere to cause an increase in resistance and a decline in gas response. Argon-ion etching or annealing of the samples in atmospheric air largely removes the morphological changes in the aged film surface. It has been observed that annealing of the film at the deposition temperature facilitates to go back to the initial response value.